whats an event that juror #3 damaged his view of young men

Juror #3 has a strained, non-existent relationship with his own son.  He thus sees the defendant as a "repeat" of the let down he felt about his own son and cannot see the defendant as anything else except his missing son.  While the reader perhaps believes that Juror #3 drove his son away, he cannot separate his son and the defendant.